title: The relationship between consumption of tyrosine and phenylalanine as precursors of catecholamine at breakfast and the circadian typology and mental health in Japanese infants aged 2 to 5 years.
abstract: BACKGROUND
  This study aims to examine the relationship between tyrosine and phenylalanine intake at breakfast as precursors of dopamine, and scores on the Torsvall-Åkerstedt Diurnal Type Scale and of mental health in Japanese infants aged 2 to 5 years.
  
  
  RESULTS
  An integrated questionnaire was administered to parents of 1,367 infants attending one of ten nursery schools governed by Kochi City or a kindergarten affiliated with the Faculty of Education at Kochi University (775 answers for analysis: 56.7%) in May and June 2008. Questionnaires included the Torsvall-Åkerstedt Diurnal Type Scale and questions on sleep habits (onset, offset, quality, quantity, and so on), meal habits (content and regularity of timing), and mental health (depressive states). Amount of tyrosine and phenylalanine intake was calculated based on a breakfast content questionnaire and data on the components of amino acids in foods. Infants who ingested more than 800 mg of tyrosine or phenylalanine at breakfast per meal were more morning-type than those who ingested less than 800 mg (ANOVA: P= 0.005). However, this relationship disappeared in the ANCOVA analysis (with the covariance of tryptophan intake, P= 0.894). Infants who ingested more than 800 mg of the two amino acids at breakfast showed significantly higher mental health scores (lower frequency of depressive states) than those who ingested less than 800 mg (ANOVA: P = 0.004). This relationship remained significant when ANCOVA analysis was performed with the covariance of tryptophan (ANCOVA: P= 0.017).
  
  
  CONCLUSIONS
  These results suggest that tyrosine and phenylalanine ingested at breakfast are not related with circadian phase, but are relate with mental health in infants.
authors.affiliation: Laboratory of Environmental Physiology, Graduate School of Integrated Arts and Sciences, Kochi University, Kochi, Japan. haratets@kochi-u.ac.jp.
authors.forename: Osami
authors.initials: O
authors.lastname: Akimitsu
authors.forename: Kai
authors.initials: K
authors.lastname: Wada
authors.forename: Teruki
authors.initials: T
authors.lastname: Noji
authors.forename: Nozomi
authors.initials: N
authors.lastname: Taniwaki
authors.forename: Milada
authors.initials: M
authors.lastname: Krejci
authors.forename: Miyo
authors.initials: M
authors.lastname: Nakade
authors.forename: Hitomi
authors.initials: H
authors.lastname: Takeuchi
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Harada
mesh_terms: D000704:Analysis of Variance; D000786:Anger; D062408:Breakfast / Q000502:physiology*; D002675:Child, Preschool; D002940:Circadian Rhythm; D004032:Diet / Q000706:statistics & numerical data*; D006801:Humans; D007564:Japan; D010649:Phenylalanine; D011795:Surveys and Questionnaires; D014443:Tyrosine
chemical_list: D014443:Tyrosine; D010649:Phenylalanine